Aiming at the instability of large flow safety valve of hydraulic support under impact load,FAD500/50 large flow safety valve of mine hydraulic support was taken as the research object,according to its structure and working principle,AMESim software was used to simulate and analyze the unloading performance of safety valve when it was overloaded,and the dynamic output characteristics of pressure and flow and the movement law characteristics of valve core were obtained when the safety valve overflowed.The results show that under the impact load,the pressure overshoot and pressure overshoot rate of the safety valve are 5.9 MPa and 15%,respectively;the valve core vibrates at the opening of the safety valve,and sudden load is the main factor causing the vibration of the valve core.Finally,the experiment proves that the pressure loss of the safety valve loop increases with the increase of the emulsion flow,but the pressure loss of the safety valve is less than 7 MPa under the nominal flow from 0 to 320 L/min,and the overall operation of the system is stable.